Alternative to #2431: Decode the filenames returned from fontconfig in
the filesystemencoding.  Fix a number of buglets that did not allow
fonts with non-ascii filenames to be opened.  This involves taking
advantage of code already in FT2Font to use unicode filenames, and
encoding the filenames before passing into ttconv.
Just skip a file if its filename can not be decoded
Fix MacOSX backend post-six transition
Use the --format argument to fontconfig so we don't have to parse
anything complex ourselves.
Fix failing mathtext tests.
Better error handling with font can not be loaded by macosx backend
Skip CGContextSelectFont if font lookup fails
Merge pull request #2433 from mdboom/unicode-font-filenames

Handle Unicode font filenames correctly/Fix crashing MacOSX backend